We need to move from thinking in terms of compliance at a farm scale to compliance at a landscape scale if we are to save as many species as we can from extinction.
- Jose Manuel Ochoa-Quintero
One of the first studies to map the impact of deforestation on biodiversity across entire regions of the Amazon has found a clear ‘threshold’ for forest cover below which species loss becomes more rapid and widespread.
By measuring the loss of a core tranche of dominant species of large and medium-sized mammals and birds, and using the results as a bellwether, the researchers found that for every 10% of forest loss, one to two major species are wiped out.
This is until the threshold of 43% of forest cover is reached, beyond which the rate of biodiversity loss jumps from between two to up to eight major species gone per 10% of disappeared forest.
While current Brazilian law requires individual landowners in the Amazon to retain 80% forest cover, this is rarely achieved or enforced. Researchers say that the focus should be shifted to maintaining 50% cover – just half the forest – but over entire landscapes rather than individual farms, in a bid to stop whole regions losing untold biodiversity by slipping below the 43% threshold at which species loss accelerates.
Unless urgent action is taken to stem deforestation in key areas that are heading towards or have just dipped below the forest cover ‘threshold’ – which, according to the research team’s models, amounts to a third of the Amazon – these areas will suffer the loss of between 31-44% of species by just 2030.
“These results support the need for a major shift in the scale at which environmental legislation is applied in Brazil and the tropics,” said Dr Jose Manuel Ochoa-Quintero, from Cambridge University’s Department of Zoology, who led the study, published recently in the journal Conservation Biology.
“We need to move from thinking in terms of compliance at a farm scale to compliance at a landscape scale if we are to save as many species as we can from extinction."
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Image: Corn plantation nearby remaining forest in the Amazon region
Credit: Jose Manuel Ochoa-Quintero
Reproduced courtesy of the University of Cambridge
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